SYNOPSIS

DESCRIPTION

The psignal() and strsignal() functions locate the descriptive message
string for a signal number.
The strsignal() function accepts a signal number argument sig and returns
a pointer to the corresponding message string.
The psignal() function accepts a signal number argument sig and writes it
to the standard error. If the argument s is non-NULL and does not point
to the null character, s is written to the standard error file descriptor
prior to the message string, immediately followed by a colon and a space.
If the signal number is not recognized (sigaction(2)), the string
``Unknown signal'' is produced.
The message strings can be accessed directly through the external array
sys_siglist, indexed by recognized signal numbers. The external array
sys_signame is used similarly and contains short, lower-case abbrevia-
tions for signals which are useful for recognizing signal names in user
input. The defined variable NSIG contains a count of the strings in
sys_siglist and sys_signame.

RETURN VALUES

strsignal() a pointer to the desired message or a NULL value indicating
an error. This string is not to be freed by the caller. Beginning with
Mac OSX 10.7, this string is unique to each thread.

ERRORS

strsignal() will fail and no additional memory will be allocated if one
of the following are true:
[ENOMEM] There was insufficient memory to allocate storage
space for the return value in the running thread.